Upconversion lasers represent a class of optically-pumped lasers that oscillate at frequencies higher than those used for pumping. The lasers produce output at wavelengths from violet to red spectral regions using infrared pump wavelengths accessible with III-V semiconductor lasers. Those compact light sources are important in optical data storage, high-speed laser printers, large-screen displays, and undersea communications. Materials commonly used for upconversion lasers include Er-doped BaY.sub.2 F.sub.8 and Tm-doped YLiF.sub.4. Paz-Pujalt, Hung, Chwalek, Hrycin, Chatterjee, and Richards U.S. Ser. No. 08/186,400, filed Jan. 25, 1994, entitled "A Device for Converting Invisible and Visible Radiation to Visible Light And/Or UV Radiation", discloses articles in which a crystalline layer of Tm-doped BaYYbF.sub.8 on a substrate exhibits upconversion excitation. Still it would be desirable to integrate epitaxial films of upconversion materials on GaAs and other III-V semiconductors. Hung, Agostinelli, and Mir U.S. Ser. No 07/992 213, now U.S. Pat. No. 5,347,157, filed Dec. 7, 1992, titled "A Multilayer Structure Having a (111)-Oriented Buffer Layer" discloses a structure comprised of a GaAs substrate and a nonlinear optical waveguide epitaxially grown on the substrate.